So-called round link chains consist of concatenated individual round links. In each case, adjacent chain links are rotated with respect to each other about the longitudinal axis of the chain by 90°. Each chain link of a round link chain consists of a bent wire section, whose free ends are stub welded to each other.
In a top view onto the flat side, the chain link consists of two straight, mutually parallel sections, both transitioning at each end into semicircular arcs. The radius of the two semicircular arcs corresponds to the center separation of the straight sections The projection of such a flat lying chain link of a round link chain on a plane parallel to the flat side of the chain link is delimited by two lines, of which one is an outer line and the other is an inner line. The outer line is consequently composed of two straight sections that are mutually parallel, and two semicircular arcs, whose diameters correspond to the separation of the straight sections. The inner line extends at all locations at the same separation from the outer line, in accordance with the wire diameter.
Such round link chains are used for moving workpieces or carriers. The carriers can be, for example, pallets that are transported along a conveyance path. The chains also can be used as a load receiving mechanism of a so-called chain hoist. In the case of two-strand or multi-strand chain hoists, the chain must be guided over deflecting rollers. The deflecting rollers work in cooperation with the chain links with a positive connection. As the chain circulates over the deflecting roller, a distinction is made between standing or vertical chain links and lying or horizontal chain links. This distinction is made with respect to the deflecting roller. A lying or horizontal chain link denotes a link having one flat side that faces the rotational axis of the deflecting roller. A standing or vertical chain link is a chain link where the flat sides stand vertically on the rotational axis of the deflecting roller.
In conventional deflecting rollers known to date, only lying or horizontal chain links are used to establish a positive connection with the deflecting roller. Because of the unavoidable free play of the lying chain links, the standing chain link that is located on the running path of the chain about the deflecting roller at the vertex is considerably loaded in the process.
A chain sprocket is known from EP 0 269 557 to ensure the drive and that is adapted to the change of the chain pitch that results due to wear. During the circulation of the chain under a load over the chain sprocket, movement occurs between adjacent chain links. The movement occurs because the chain that has stretched under the load is forced by the deflecting roller in a circular track. The relative movement between the chain links causes friction wear with the consequence that the thickness of the chain link decreases at the corresponding locations. The thickness of the chain link is understood in the art to refer to the diameter of the wire at the particular location. Due to the change in the chain link thickness, the chain increases in length, i.e., its periodicity is no longer in agreement with the pitch of the deflecting roller. To take this into account, the chain pockets are shaped in a specific way for the standing or vertical chain links in known deflecting rollers.
The chain pockets for the standing or vertical chain links form a groove that runs in the peripheral direction of the chain sprocket, which groove passes through the chain pockets for the lying or horizontal chain links. The bottom of this groove describes, in the broadest sense, a regular n-gon, where n is equal to the number of chain pockets for the lying or horizontal chain links. The sides of this regular n-gon in each case are circular arc sections with a constant radius of curvature, which is very large compared to the radius of curvature of the outer line of the individual chain link. The pocket bottom has no change in curvature along its path. It merely transitions at the end into a rounded corner of the n-gon, at which the next pocket bottom for the adjacent chain pocket of a standing chain link starts. In the broadest sense, this corner can also be understood to be a tooth. The tooth tip is located at the middle, i.e., centered in the chain pocket for the lying or horizontal chain element. It ends considerably below a plane that is defined by the flat side of the chain link that is adjacent to the rotation axis.
FIG. 2 of the aforementioned EP 0 269 557 shows the ratio between the standing or vertical chain link and the associated chain pocket when employing a previously unused round link chain. The adjacently lying or horizontal chain links hold the standing or vertical chain link at a separation from the pocket bottom of the chain pocket for the corresponding standing chain link. It is only when the chain length increases due to wear that there is a slight cant of the standing chain link, with the consequence that the chain link bears with its nose that points in the loading direction against the pocket bottom. The tangent at the contact point between the pocket bottom and the outer line of the chain link runs at a very acute angle with respect to the longitudinal axis of the standing chain link, with the result that practically no force transmission is possible through the point-shaped contact location, from the deflecting roller to the round link chain or vice versa.